HE 0107–5240, a Chemically Ancient Star. I. A Detailed Abundance Analysis

By N. Christlieb, B. Gustafsson, A. Korn, Paul Barklem, Timothy C. Beers, M. Bessell, T. Karlsson, M. Mizuno-Wiedner. 2003

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We report on a detailed abundance analysis of HE 0107-5240, a halo giant with [Fe/H]NLTE = -5.3. This star was discovered in the course of follow-up medium-resolution spectroscopy of extremely metal-poor candidates selected from the digitized Hamburg/ESO objective-prism survey. On the basis of high-resolution VLT/UVES spectra, we derive abundances for eight elements (C, N, Na, Mg, Ca, Ti, Fe, and Ni) and upper limits for another 12 elements. A plane-parallel LTE model atmosphere has been specifically tailored for the chemical composition of HE 0107-5240. Scenarios of the origin of the abundance pattern observed in the star are discussed. We argue that HE 0107-5240 is most likely not a post-asymptotic giant branch star and that the extremely low abundances of the iron-peak and other elements are not due to selective dust depletion. The abundance pattern of HE 0107-5240 can be explained by preenrichment from a zero-metallicity Type II supernova (SN II) of 20-25 M☉, plus either self-enrichment with C and N or production of these elements in the asymptotic giant branch phase of a formerly more massive companion, which is now a white dwarf. However, significant radial velocity variations have not been detected within the 52 days covered by our moderate- and high-resolution spectra. Alternatively, the abundance pattern can be explained by enrichment of the gas cloud from which HE 0107-5240 formed by a 25 M☉ first-generation star exploding as a subluminous SN II, as proposed by Umeda & Nomoto. We discuss consequences of the existence of HE 0107-5240 for low-mass star formation in extremely metal-poor environments and for currently ongoing and future searches for the most metal-poor stars in the Galaxy.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/50e0af01e3355dcf9459f4cd4262ca7305e566e5

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Citations in the corpus

Binarity in carbon-enhanced metal-poor stars (2014, background): “In particular, four out of the fiv stars known with [Fe/H]<-4.5 seem to be consistent with the CEMPno class (Christlieb et al. 2004; Frebel et al. 2005; Aoki et al. 2006; Norris et al. 2007; Keller et al. 2014, although in some casesonly an upper limit for barium could be derived).”
NUCLEOSYNTHESIS AND EVOLUTION OF MASSIVE METAL-FREE STARS (2008, methodology): “Comparison with the Ultra-Iron-poor Stars The stars HE0107-5240 (Christlieb et al. 2004, 2007; Bessell et al. 2004; Frebel et al. 2005; Collet et al. 2006) and HE13272326 (Frebel et al. 2005, 2006, 2008; Aoki et al. 2006; Collet et al. 2006) may be representative of a larger class of stars that show”
Is HE 0107–5240 A Primordial Star? The Characteristics of Extremely Metal-Poor Carbon-Rich Stars (2004, background): “Then, 8-30 subsequent third dredge-up episodes (during which only the isotope 12C is added) lead to a surface ratio 12C/13C ∼ 32 − 120, which is consistent with the estimate for HE0107-5240 of 12C/13C > 50 (Christlieb et al. 2004).”
Evolution of Dust in Primordial Supernova Remnants: Can Dust Grains Formed in the Ejecta Survive and Be Injected into the Early Interstellar Medium? (2007, background): “…Iwamoto et al. 2005), the nucleosynthesis and mass transfer in a first-generation binary star (Suda et al. 2004; Komiya et al. 2007), the pollution by the gas with heavy elements in the ISM (Shigeyama et al. 2003), and the combinations of these scenarios described above (Christlieb et al. 2004).”
HIGH-RESOLUTION SPECTROSCOPY OF EXTREMELY METAL-POOR STARS IN THE LEAST EVOLVED GALAXIES: URSA MAJOR II and COMA BERENICES (2009, background): “−3.5 have very low neutron-capture abundances (e.g., Sr and Ba; Norris et al. 2001), and this trend is also found in two of the three halo stars known with [Fe/H] < −4.0 (Christlieb et al. 2004; Norris et al. 2007).”
Three-dimensional hydrodynamical simulations of surface convection in red giant stars: impact on spectral line formation and abundance analysis (2007, background): “…a set of low-excitation (0 to 0.5 eV) features representa- tive of molecular bands frequently used in abundance analyses of giants (e.g. Christlieb et al. 2004; Bessell et al. 2004; Cayrel et al. 2004; Spite et al. 2005): CH lines at 4360 Å belonging to the A−X electronic transition…”
Evolution of Asymptotic Giant Branch Stars (2005, background): “The most metal-poor star observed to date is HE 0107-5240 with [Fe/H]= −5.3 (Christlieb et al. 2004).”
THE DISCOVERY AND ANALYSIS OF VERY METAL-POOR STARS IN THE GALAXY (2005, methodology): “THE ABUNDANCE PATTERNS OF HMP STARS The abundance patterns of HE 0107−5240 (Christlieb et al. 2002, 2004; Bessell, Christlieb & Gustafsson 2004) and HE 1327−2326 (Frebel et al. 2005; W. Aoki, A. Frebel, N. Christlieb, J.E. Norris, T.C. Beers, et al., in preparation) are characterized by huge…”
THE MOST METAL-POOR STARS. II. CHEMICAL ABUNDANCES OF 190 METAL-POOR STARS INCLUDING 10 NEW STARS WITH [Fe/H] ⩽ −3.5,, (2012, background): “HE 0107−5240 (Christlieb et al. 2002, 2004), HE 1327−2326 (Frebel et al. 2005; Aoki et al. 2006), and HE 0557−4840 (Norris et al. 2007), within the Hamburg/ESO Survey (HES; Wisotzki et al. 1996), and SDSS J102915+172927 (Caffau et al. 2011), in the Sloan Digital Sky Survey Data Release 7 (Abazajian…”
The First Cosmic Structures and Their Effects (2004, background): “…star was born, or (ii) their origin is due to a post-formation mechanism, such as mass transfer from a companion star, self-enrichment from the star itself or accretion due to repeated passage through the Galactic disk (for a thorough discussion of these issues we refer to Christlieb et al. 2004).”
A grid of MARCS model atmospheres for late-type stars. I. Methods and general properties (2008, background): “The most metal-poor stars known until now show severe departures from “standard” CNO abundances: they seem to be comparatively very rich in CNO elements (cf., Christlieb et al. 2004; Frebel et al. 2005; Norris et al. 2007, and references therein).”
Abundances In Very Metal-Poor Dwarf Stars (2004, methodology): “Cayrel et al. (2003) succeeded in adding two stars to the six previously known to have [Fe/H] ≤ −3.5 dex, five of which are studied in detail in Norris, Ryan & Beers (2001) and the most iron-poor of all, with [Fe/H] = −5.3 dex (found in the HES), is analyzed by Christlieb et al. (2004).”